Single-crystal x-ray diffraction structures of covalent organic frameworks
Single-crystal x-ray diffraction structures of covalent organic frameworks
复制标题
共价有机骨架的单晶X射线衍射结构
DOI：
10.1126/science.aat7679
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发表时间：
2018-07-06
期刊：
影响因子：
56.9
通讯作者：
Yaghi, Omar M.
中科院分区：
文献类型：
--
作者：
Ma, Tianqiong;Kapustin, Eugene A.;Yaghi, Omar M.
共价有机骨架是一种很大的有机骨架材料，由于其易形成粉末或无定形材料，其结构难以表征和开发。Ma等人。研究了基于亚胺连接的各种三维COF(见Navarro的透视法)。他们发现，苯胺的加入抑制了成核，并允许生长出足够大的晶体，以进行单晶X射线衍射研究。埃文斯等人。描述了一种两步法，在该过程中，通过使用抑制额外纳米颗粒成核的溶剂，可以将纳米级的硼酸酯连接的二维COF的种子生长成微米级的单晶。瞬时吸收光谱表明，与传统粉末相比，这些微晶具有更好的电荷传输性能。科学，本期第48页，第52页；另见第35页。苯胺的加入使亚胺基共价有机骨架材料的单晶得以生长。结晶问题是多孔共价有机骨架(COF)化学中的一个突出挑战。它们的结构表征仅限于基于粉末X射线或电子衍射数据的建模和解决方案。具有X射线衍射表征能力的COF单晶尚未见报道。在这里，我们开发了一个通用的程序来生长三维亚胺基碳纤维(COF-300，水合形式的COF-300，COF-303，LZU-79和LZU-111)的大单晶。晶体的高质量允许收集高达0.83埃分辨率的单晶X射线衍射数据，从而实现明确的解决方案和精确的各向异性精细化。特征，如相互渗透的程度，水客体的排列，反向亚胺连接，连接子无序，以及罕见的拓扑结构，都是用原子的精确度破译的--如果没有单晶体，就不可能确定这些方面。
Covalent organic frameworks writ large Covalent organic framework (COF) materials have been difficult to characterize structurally and to exploit because they tend to form powders or amorphous materials. Ma et al. studied a variety of three-dimensional COFs based on imine linkages (see the Perspective by Navarro). They found that the addition of aniline inhibited nucleation and allowed the growth of crystals large enough for single-crystal x-ray diffraction studies. Evans et al. describe a two-step process in which nanoscale seeds of boronate ester–linked two-dimensional COFs can be grown into micrometer-scale single crystals by using a solvent that suppresses the nucleation of additional nanoparticles. Transient absorption spectroscopy revealed superior charge transport in these crystallites compared with that observed in conventional powders. Science, this issue p. 48, p. 52; see also p. 35 The addition of aniline enables the growth of single crystals of imine-based covalent organic framework materials. The crystallization problem is an outstanding challenge in the chemistry of porous covalent organic frameworks (COFs). Their structural characterization has been limited to modeling and solutions based on powder x-ray or electron diffraction data. Single crystals of COFs amenable to x-ray diffraction characterization have not been reported. Here, we developed a general procedure to grow large single crystals of three-dimensional imine-based COFs (COF-300, hydrated form of COF-300, COF-303, LZU-79, and LZU-111). The high quality of the crystals allowed collection of single-crystal x-ray diffraction data of up to 0.83-angstrom resolution, leading to unambiguous solution and precise anisotropic refinement. Characteristics such as degree of interpenetration, arrangement of water guests, the reversed imine connectivity, linker disorder, and uncommon topology were deciphered with atomic precision—aspects impossible to determine without single crystals.